Add check whether compiler supports -march=native flag

Signed-off-by: Stefan Weil <sw@weilnetz.de>

Author: stweil

configure.ac

@@ -115,6 +115,7 @@ esac
 AM_CONDITIONAL([AVX_OPT], false)
 AM_CONDITIONAL([AVX2_OPT], false)
 AM_CONDITIONAL([SSE41_OPT], false)
+AM_CONDITIONAL([MARCH_NATIVE_OPT], false)
 
 AX_CHECK_COMPILE_FLAG([-mavx], [avx=true], [avx=false])
 if $avx; then
@@ -131,6 +132,11 @@ if $sse41; then
     AM_CONDITIONAL([SSE41_OPT], true)
 fi
 
+AX_CHECK_COMPILE_FLAG([-march=native], [arch_native=true], [arch_native=false])
+if $arch_native; then
+    AM_CONDITIONAL([MARCH_NATIVE_OPT], true)
+fi
+
 AC_ARG_WITH([extra-includes],
             [AS_HELP_STRING([--with-extra-includes=DIR],
                        [Define an additional directory for include files])],

src/arch/Makefile.am

@@ -29,7 +29,10 @@ if SSE41_OPT
 libtesseract_sse_la_CXXFLAGS = -ffast-math -msse4.1
 endif
 
-libtesseract_native_la_CXXFLAGS = -O3 -ffast-math -march=native -mtune=native
+libtesseract_native_la_CXXFLAGS = -O3 -ffast-math
+if MARCH_NATIVE_OPT
+libtesseract_native_la_CXXFLAGS += -march=native -mtune=native
+endif
 libtesseract_native_la_SOURCES = dotproduct.cpp
 
 libtesseract_arch_la_SOURCES = intsimdmatrix.cpp simddetect.cpp